In this Phase II project, the goal is to continue development and validate the radiation toxicity (RadTox) diagnostic test. We will also explore if gene expression in blood can be used to predict radiation sensitivity. In our Phase I study, gene expression based biomarkers were identified, the DxDirect based assay was developed, and the prototype predictor algorithm was developed. In Phase II the sample size will be increased to at least 500 patients, confounders will be identified, the gene expression assay will be further developed and validated, and the locked assay will be transferred to DxTerity?s CLIA/CAP laboratory for initial commercialization. We will also begin Quality System Regulation (QSR) compliant product development. During this Phase II SBIR contract, we will complete Phase 0 and Phase 1 of product development. DxTerity?s long term intention is to submit the assay for eventual FDA clearance with the intention of being a product line upgrade to DxTerity?s REDI-Dx: High Throughput Biodosimetry assay.